1. Field of the Invention
The present invention relates generally to electrical switching apparatus and, more particularly, to a tool for resetting a circuit breaker indicator, such as, for example, a movable arc fault indicator. The invention also relates to a circuit breaker including a reset tool for engaging a movable arc fault indicator. The invention further relates to a method for engaging and resetting a movable arc fault indicator.
2. Background Information
Circuit breakers traditionally have provided overcurrent protection through use of, for example, a bimetal coupled to a spring-loaded operating mechanism. Recently, arc fault protection has been added to circuit breakers. Arc faults are typically high impedance faults and can be intermittent. Nevertheless, such arc faults can result in a fire.
The addition of electronic arc fault sensing to a circuit breaker can add one of the elements required for sputtering arc fault protection. Ideally, an electronic circuit detects current signatures associated with arcing, and an arc fault trip signal generated by the electronic circuit energizes a trip coil that triggers the spring-loaded operating mechanism to open the separable contacts of the circuit breaker.
However, it is often desirable in circuit breakers providing both arc fault protection and overcurrent protection to provide an indication of the type of fault that has caused the breaker to trip. An example of a separate arc fault indicator can be seen in commonly assigned U.S. patent application Ser. No. 09/845,517, filed Apr. 30, 2001, now U.S. Pat. No. 6,522,228, which discloses a movable, illuminated ring disposed around the push/pull handle of a subminiature circuit breaker. The ring pops up to indicate an arc fault trip condition.
In certain applications, particularly aircraft electrical systems, certain circuits are so critical that manual intervention by a crewmember may be desirable before a circuit is de-energized, for example, without limitation, certain avionic and navigation instrumentation, electric fuel pumps, and electrical components of the landing gear system. The vital nature of such systems may necessitate in flight manual override or reset of a circuit breaker, which was tripped open by an arc fault, as indicated by an arc fault indicator, in order to safely continue the flight until the aircraft can land and repairs can be made. The arc fault indicator may be reset, either in flight, or, more commonly, following maintenance repairs on the ground.
There is, therefore, a need to quickly, easily, and economically reset the arc fault indicator of a circuit breaker.
This need and others are satisfied by the invention, which is directed to a tool for resetting circuit breaker indicators and a method employing the same.
As one aspect of the invention, an indicator reset tool is used with an electrical switching apparatus, which includes a housing having an opening, separable contacts mounted within the housing, an operating mechanism for opening and closing the separable contacts, an operating handle protruding from the opening of the housing, a movable indicator, and an actuator for actuating the movable indicator and actuating the operating mechanism to trip the separable contacts open, the indicator reset tool comprises: a reset member including a first end a second end, the first end of the reset member having an indicator engaging portion structured to depress and reset the movable indicator when actuated, the second end of the reset member having a handle portion structured for gripping by a user.
As another aspect of the invention, a circuit breaker comprises: a housing with an opening; an operating handle protruding from the opening; separable contacts mounted within the housing; an operating mechanism for opening and closing the separable contacts; an overcurrent assembly responsive to selected conditions of current flowing through the separable contacts for actuating the operating mechanism to trip the separable contacts open; a movable arc fault indicator; an arc fault trip actuator which when energized actuates the movable arc fault indicator and actuates the operating mechanism to trip the separable contacts open; an arc fault current assembly responsive to selected arc fault conditions of current flowing through the separable contacts for energizing the arc fault trip actuator to actuate the movable arc fault indicator and to activate the operating mechanism to activate the operating mechanism to trip the separable contacts open; and a reset tool comprising: an elongated handle member; and an indicator engagement portion disposed opposite the elongated handle member, the indicator engagement portion structured to engage and reset the movable arc fault indicator.
As another aspect of the invention, a method for resetting an arc fault indicator of a circuit breaker comprises: employing a circuit breaker including a housing with an opening through which an operating handle protrudes; providing a movable arc fault indicator; providing a reset tool with a handle member and an indicator engagement region structured to engage the movable arc fault indicator; holding the handle member of the reset tool; engaging the movable arc fault indicator with the indicator engagement region of the reset tool; and pressing downward on the handle member in order that the indicator engagement region depresses and resets the movable arc fault indicator.
The method may comprise: providing a first circumference on the operating handle; providing a recess in the indicator engagement region of the reset tool, with the recess corresponding to the first circumference of the operating handle; providing a second circumference on the movable arc fault indicator; providing a projection on the indicator engagement region, with the projection corresponding to the second circumference of the movable arc fault indicator; and engaging at least a portion of the movable arc fault indicator with the projection of the indicator engagement portion of the reset tool.
The method may comprise engaging at least a portion of the operating handle with the recess of the indicator engagement portion of the reset tool.